Vacuum tube



Nov. 10, 1925.

C. F. M., HAYES ET AL VACUUM TUBE Filed Feb. 10, 1925 Patented Nov. 10,1925.

UNITED STATES PATENT OFFICE.

cmnns rnnnnmc MARCHAN'I nevus AND LESLIE enms'rnan, or Lomion, ENG-LAND, ASSIGNORS To run mU LAnn RADIO vALvn courmr nmrrnn, n BRITISHCOMPANY.

VACUUM TUBE.

Application filed February 10, 1925. Serial No. 8,222.

To all whom it may concern:

Be it known that we, CHARLES Fnnonnrc MARCHANT HAYEs and LnsnmGRINSTEAD, British subjects, and residents of Nightingale Lane, Balham,London, S. 'W. 12, England, have invented certain new and usefulImprovements in Vacuum Tubes (for .which we have filed an application inEngland, dated 3rd May, 1924), of which the following is aspecification.

This invention relates to thermionic valves or electron discharge tubesand is particularly concerned with the support or fixing of theelectrodes, particularly the grid and anodes of'thermionic valves and isespecially applicable to the construction of large valves such as areused fortransmitw ting purposes although it is in no sense limited totransmitting valves.

According to the invention, a band of metal is placed in positionembracing a reentrant tube or stem of the valve bulb and carries theelectrode in question by means of a number of legs and is ultimatelyfixed in position by the insertion of wedges which may comprise separatemembers, or may be formed by the ends of the electrode legs. The wedgesor legsmay be fixed in position either by spot Welding at a number ofpoints to the embracing band or in the case of the legs serving aswedges, wires may be welded to theleg and to the band and the formerretained in position by twisting the two wirestogether. In order thatinvention ma be clearly understood and readily carrie into effect, someforms of construction for fixing electrodes in position in accordancewith the invention are illustrated. in the accompanying drawings, inwhich I Figure 1 is an elevation of a complete thermionic valve with thewalls of the bulb in section, showing both the anode and grid secured inposition in accordance with the present invention; s Figure 2 1s aperspective view of one stem of the valve shown in Figure 1 but withoutthe supporting legs attached to the clip;

Figure 3 is a'horizontal section on the line III-III of Figure 2, but inan intermediate stage of construction, wherein the welded edges of theclip are not turned down against the outer wall of the clip; and

Figures 4: and 5 are views similar to Figure 2, but showing twoalternative constructions wherein the legs of the electrode form thesecuring wedges.

Referring first to Figures 1 to 3, a metal band a is placed in positionaround the glass stem or re-entrant tube 6 which is sealed into thewalls a of the valve at one end. As can be seen the metal band forms aring which does not fit the foot I) but leaves a free space. This isparticularly clearly seen in Figure 3. The meeting edges (1, e of theband a are turned radially outwards so as to lie in contact as clearlyseen in Figure 3 and are then spot welded together at a number of pointsas indicated at f in Figure 2., The out-turned edges (1, e can be leftprojecting radially as in Figure 3, but in Figures 2, 4 and 5 they areshown as folded down into contact with the outer cylindrical surface ofthe metal band a. In this condition the band forms a completecylindrical ring entirely surrounding the stem or reentrant tube 6, but,as already mentioned, it is of such a size that it does not grip thefoot I). It is subsequently fixed in position by one or more metalwedges g, there being actually three of such wedges in Figures 1 to 3 ofsegmental section. They are slipped in between the metal band a and theglass stem 6 and aresecured in the example illustrated by spot weldingat the points h, although if desired other methods of securing may beemployed. In Figure 1 this method of securing the anode is shown at thebottom of the valve and a similar method is shown at the top of thevalve for securing the grid Z. In both cases in Figure 1 the legs m areshown secured to the metal band a by being spot welded on the outersurface of this band. The legs may, however, in

fact be made integral with the band a or may be riveted thereto.

As alread indicated, in Figures 4 and 5 I the legs m t emselves serve asthe securin wedges, but. otherwlse the construction is similar to thatshown in Figure 2 and similar .and electrodes therein,

reference letters have been applied. There are a number of ways ofmaintaining the legs in position when they serve as the wedges, forexample in Figure 4 they are secured in position by spot welding asindicated at n. In the alternative form in Figure 5, however, each legon has a wire 0 welded to it at a point a short distance away from theupper edge of the metal band a and the band a has a wire 7) for each legwelded to it at a point in the neighborhood at which the end of the legm enters the band a. The wires 0, p are twisted together in pairs asshown in Figure 5' in order to hold the respective legs firmly wedgedwithin the band a. In Figure 5 spot welding is also indicated forsecuring the legs in posit-ion at a, but the method of securing by thewires 0, p can be employed without spot welding at a without departingfrom the scope of the present invention.

Having thus described our invention what we claim as new and desire tosecure by Letters Patent is 1. In a vacuum tube having an envelope andelectrodes therein, the combination of a bandloosely encircling a stemon said envelope and supporting one of the electrodes, and a wedgeinserted between said band and said foot.

2. In a vacuum tube having an envelope and electrodes therein. thecombination of a band loosely encircling a stem on said envelope andsupporting one of the electrodes, and a plurality of wedges spacedaround the stem and inserted between said band and said foot.

3. In a vacuum tube having a envelope and electrodes therein, thecombination of a band loosely encircling a stem on said envelope andsupporting one of the electrodes, and a wedge inserted between said bandand said stem and welded to said band.

4. In a vacuum tube having an envelope an electrodes therein, thecombination of a band loosely encircling a stem on said envelope andsupporting one of the electrodes, and a plurality of wedges spacedaround the stem and inserted between said band and said stem, saidwedges being welded to said band.

5. In a vacuum tube having an envelope and electrodes therein, thecombination of a band loosely encircling a stem on said envelope and anelectrode supported on legs, said legs being inserted between said bandand said stem to act as wedges to secure said band in position.

6. In a vacuum tube having an envelope the combination of a band looselyencircling a stem on said envelope and an electrode supported on legs,said legs being welded to said band between the band and said stem, andacting as wedges to secure said band in position.

7. In a vacuum tube having an envelope containing grid and anodeelectrodes and furnished with two re-entrant stems disposed at oppositeends of said envelope, the combination of a band loosely encircling oneof said stems and supporting said grid electrode, wedges insertedbetween said band and said stem,a second band loosely encircling theother of said stems and supporting said anode, and further wedgesinserted between said second hand and said second named stem.

8. In a vacuum tube having an envelope with two re-entrant stemsdisposed at opposite ends of said envelope, thecombination of a bandloosely encircling one of said stems, a grid electrode with integrallegs, said legs being inserted between said band and said stem andacting as wedges to secure said band in position, a second band looselyencircling the second of said stems and an anode with integral legs,said legs bein inserted between said second hand and sai second stem andacting as wedges to secure said second hand in position.

9. A method of mounting an electrode within a vacuum tube envelope witha reentrant stem which consists in bending a metal strip to form a bandloosely encircling said stem and having two radial flanges in contactwith each other, spot welding said adjoining flanges together, therebyforming said strip into a continuous band and driving in a wedge betweensaid band and said stem to secure an electrode to said stem.

10. A method of mounting an electrode within a vacuum tube envelope witha 'reentrant stem which consists in bending a metal strip to form a bandloosely encircling said stem and having two radial flanges in contactwith each other, spot welding said adjoining flanges together, therebyforming said strip into a continuous band, turning down said flanges tolie circumferentially against said band and driving in a wedge betweensaid band and said stem to secure an electrode to said stem.

11. A method of mounting an electrode with integral legs within a vacuumtube envelope with a re-entrant stem which consists in bending a metalstrip to form a band loosely encircling said stem and having two radialflanges in contact with each other, spot Welding said adjoining flanges,thereby forming said strip into a continuous band, and inserting thelegsof said electrode between said band and said stem to wedge said bandupon said foot'and thereby to secure said electrode firmly in position.

12. A method of mounting a grid electrode and an anode within a vacuumtube envelope having two re-entrant stems at opposite ends whichconsists in bending two metal strips to form each into a band looselyencircling one of said stems and having two radial flanges in contactwith each other, spot welding the flanges of each band together, therebyformin each of said strips into a continuous ban and inserting betweenthe ,one band and the one stem the legs of the gria and between theother band and the other stem the -legs of the anode to act as. wedgesand to secure said electrodes respectively firmly in position.. I

In witness whereof, we hereunto subscribe our names this 1925.

' CHARLES EREDERIC MARCI IAN'I' HAYES.

LESLIE GRINSTEAD.

29th day of J anuary, A. D.

